Device for cooling a tuyere of a refining converter

ABSTRACT

Means for cooling a tuyere of a refining converter having two separate feed systems, which comprises an axial circuit for the oxidizing gas and a peripheral circuit for the cooling agent, wherein a cooling liquid, such as water under pressure, carbon dioxide in the liquid state or a hydrocarbon-containing liquid is injected into the peripheral circuit in lieu of a cooling gas.

United States Patent 1 Leroy et a1.

[11] 3,779,534 Dec. 18, 1973 DEVICE FOR COOLING A TUYERE OF A REFINING CONVERTER [75] lnventors: Pierre Leroy, St. Germain en Laye;

Marcel Gombert, Moyeuvre-Grance; Metz Queuleu, Moyeuvre-Grance; Emile Sprunck, Moyeuvre-Grance, all of France [73] Assignee: Creusot-Loire a societe anonyme,

Paris, France [22] Filed: May 15, 1972 [21] Appl. No.: 253,400

Related US. Application Data [62] Division of Ser. No. 50,393, June 29, 1970,

abandoned. i

[30] Foreign Application Priority Data July s. 1969 France 692s1'4s Nov; 13, 1969 France.... 6938923 June 23, 1970 France 6.923078 [52] US. Cl 266/41, 75/60, 266/35 [51] Int. Cl. C2lc 5/34 Primary Examiner-Gerald A. Dost Alto rney E. F. Wenderoth et a1.

[ ABSTRACT Means for cooling a tuyere of a refining converter having two separate feed systems, which comprises an axial circuit for the oxidizing gas and a peripheral circuit for the cooling agent, wherein a cooling liquid, such as water under pressure, carbon dioxide in the liquid state or a hydrocarbon-containing liquid is injected into the peripheral circuit in lieu of a cooling gas.

(Claims, 4 Drawing Figures //////X i i\\\\ 1 f DEVICE FOR COOLING A TUYERE OF A REFINING CONVERTER This application is a Division of application Ser. No. 50,393 filed June 29, 1970, entitled Method and Device for Cooling a Tuyere of Refining Converter, now abandoned."

BACKGROUND OF THE INVENTION This invention relates to improvements in devices for cooling the tuyere of a refining converter, more particularly of a submerged tuyere blowing in an upward direction, either vertically or obliquely.

It'is known to retard the wear of a refiningconverter tuyere by surrounding the main jet consisting of an oxidizing gas, for example pure oxygen, with a peripheral shield" consisting of a cooling gas, such as water steam, carbon dioxide gas, gaseous hydrocarbons, etc. Consequently in such tuyere, comprising two separate feed means, there'is an axial circuit for the oxidizing gas and a peripheral or concentric circuit for the cooling gas. I Y

The conditioning of cooling gases is attended by certain difficult problems, and their cost affects the refining operation depending on the nature of the gas utilized.

Moreover, when using a cooling gas the resultant SUMMARY" OF THEINVENTION It is the primary object of this invention to provide a means to improve the cooling of the' tip of the tuyere while reducing the consumption of cooling fluid, by resorting also to vaporization heat.

To this end the present invention provides'a device for cooling the tuyere of a refining converter'which comprises a double, separate feed system, characterized in that a cooling liquid such as water under pressure, liquid carbon dioxide or a hydrocarboncontaining liquid is injected into the peripheral circuit in lieu of a cooling gas.

According to a specific feature of the use-of this invention, the cooling liquidis introduced into' a gap formed between two concentric tubular ducts, this gap being of annular or other configuration. I If water under pressure is used as a cooling medium it is introduced into the peripheralLcircuit of each tuyere, possibly after preheating for example at 80C. (176F).

According to this invention, in order to obtain a cooling liquid circulation rate high enough to cause the vaporizationto take place at the tip of the tuyere, it is contemplated to use an oxygen delivery duct having a cross-sectional passage area at least 30 times greater than that of the liquid passage duct in each tuyere.

According to the use of the device of this invention, to avoid the introduction of liquid coolant into the converter, since this would cause an immediate vaporization of the coolant, the initial part of the blowing process is performed by introducing the oxidizing gas, for example pure oxygen, into the peripheral circuit and at the same time into the axial circuit, and after the beginning of the metal melt refining process, by producing a switching" or reversal whereby the-selected liquid under pressure is substituted for the oxidizing gas in the peripheral circuit alone.

According to a specific feature characterizing the use of this invention, if carbon dioxide is used as the cooling agent, the pressure and temperature thereof are in all cases selected with a view to keep the product'in the liquid state until it penetrates into the tuyere, this pressure and temperature being advantageously of 5 to 25 bars (72 to 365 psi) and -45 to 3C (49 to 8.6F) respectively, in which case the density of the liquid carbon dioxide differs but slightly from that of water.

According toanother specific feature of the use of this invention, there are utilized in succession as the cooling agent, firstly water and then liquid carbon dioxide, or conversely, firstly liquid carbon dioxide and then water, in the same set of tuyeres.

According to another feature characterizing the use of this invention, which is advantageous notably in the production of low-hydrogen steel grades, the first part of the conversion is carried out by using water as a tuyere cooling agent, and the second part of the conversion is carried out by using liquid carbon dioxideas a cooling agent. Thus,'-the stirring of the-metal melt by the carbon monoxide resulting from the decomposition of the carbon dioxide makes it possible to release the hydrogen contained in the melt before the conversion process is completed.

The chief advantage resulting from the use of liquid carbon dioxide, in comparison with the use of water, is that very low hydrogen contents can be obtained in the steel, and in comparison with the use of carbon dioxide gas, that the undesired but necessary preliminary evaporation can be avoided, as this evaporation requires the use of a special, cumbersome equipment, while taking advantage of the improved cooling capacity per weight unit of liquid carbon dioxide utilized, since a cooler product is used, the vaporization of which will absorb additional heat from the tip of the tuyere.

Another advantage is that it is relatively easy to switch from water to liquid carbon dioxide, or viceversa, in a same set. of tuyeres,since both liquids have approximately the same density. I

I-Iowever, particular care must be exerted throughout the circuit for avoiding local expansions of the liquid carbon dioxide which might cause the formation of carbonic acid snow likely to clog the circuit.

When using in this invention a hydrocarbon contain ing liquid as a coolant a still better cooling effect at the tipof the tuyere is obtained by taking advantage, furthermore, of the heat released by the dissolution of carbon in molten steel, but still without resorting to a gaseous cooling agent. 4'

According to the use of this invention, a hydrocarbon-containing cooling liquid may be fuel-oil whether of domestic grade, or light fueloil, or heavy oil, or

- geous for producing low-hydrogen steel grades, the first part of the conversion process is carried out by utilizing a hydrocarbon-containing liquid as a cooling agent and the second part by utilizing liquid or gaseous carbon dioxide.

Another feature characterizing the use of this invention consists in introducing a scavenging gaseous stream consisting of atmospheric air or neutral gas into the tuyere when the supply of oxidizing gas blown through the axial circuit, or the supply of cooling liquid, is discontinued.

According to a complementary feature characterizing the use of this invention, the desired cooling liquid output is adjusted by using means such as volumetric pumps for introducing the cooling liquid, by varying the pump pressure irrespective of the possible variations in the cross-sectional passage area available for the liquid at the tip of the tuyere, as a consequence for example of partial clogging due to metal having set therein, and followed by a partial or complete remelting of the deposits thus formed.

This invention is concerned with a device comprising two concentric tubes having very close diameters in mutual telescopic or sliding engagement. Rectilinear splines or grooves are provided at the limit of the two concentric tubes for introducing the cooling liquid. These splines may be machined on the outer face of the inner tube, the latter being slidably mounted in the outer tube with a very small clearance therebetween, and these splines may extend transversely and have a circular or semi-circular cross-section, or constitute circular segments.

According to a modified embodiment of this invention, the device comprises, for introducing the cooling liquid, an annular space formed between a pair of concentric tubes. The tubes are concentrically spaced by point protrusions.

Other features and advantages of this invention will appear as the following description proceeds with reference to the attached drawings illustrating diagrammatically by way of example various forms of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are a vertical axial section and a horizontal cross-section, respectively, of a first embodiment of the invention, and

FIGS. 3 and 4 are similar views showing another'embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION In the first embodiment of the invention (FIGS. 1 and 2) applicable to a tuyere of relatively small diameter the device comprises, for blowing pure oxygen, a copper tube having an inner diameter of for instance 3 mm and an outer diameter of for instance 6 mm, sliding with a very moderate play in an outer metal tube 12 having an outer diameter of for instance 8 mm and an inner diameter of for instance 6 mm. On the outer face of the inner tube 10, eight rectilinear splines or grooves 14 having a radius of for instance 0.3 mm are machined at angular intervals of 45 from one another, their cross-sectional contour being substantially semicylindrical. If water under pressure is used as a cooling agent, a suitable output is obtained for an 0 output of 300 to 400 liters per minute and a 12 inch-long tuyere.

In the second embodiment of the invention (FIGS. 3 and 4) the tuyere has a larger diameter and comprises for blowing oxygen a copper tube 16 centered at spaced points in an outer tube 18. The centering of tube 16 within tube 18 is achieved by point protrusion 22 which may be on the inner surface of outer tube 18 as shown, or as with grooves 14 of the first embodiment, may be located on the outer surface of the inner tube. The annular space 20 is such that the cooling liquid output (water under pressure) is adequate, in this example, for an oxygen output of 7 to 10 Nm lmin.

This device of the present invention has the following advantages:

low cost of the cooling agent,

the conditioning of the liquid cooling agent is easier than that of gaseous agents;

high pressures can be obtained and distributed with greater ease.

However, cooling according to the use of this invention by using a hydrocarbon-containing liquid is attended by the following advantages in comparison with water cooling: the cooling effect resulting from the vaporization heat, the heating due to overheating and the dissociation heat, is completed by the effect resulting from the heat released as a consequence of the carbon dissolved in the metal melt, and thus leads. to a lower consumption of hydrocarbon-containing cooling liquid than if water alone were used, or alternatively to an improved cooling effect at the tip of the tuyere.

Two specific ways of using this invention will be described by wayof example, not of limitation:

The first relates to the cooling of tuyeres by using domestic fuel-oil having a density of 0.84.

The second relates to the cooling of tuyeres by using a mixture of water and domestic fuel-oil, in the proportion of 50/50.

During the following description reference will be i made to FIGS. 1 and 2 illustrating above-described tuyere which, except for the dimensions, may be used in the examples described hereinafter.

This tuyere comprises, for blowing pure oxygen, a copper tube 10 having an inner diameter of l l mm and an outer diameter of 14 mm, which slides with a very small clearance in an outer metal tube 12 having an inner diameter of 14 mm and an outer diameter of 16 mm.:. On the outer surface of the copper tube there are machined eight rectilinear splines or grooves 14 of crescent-shaped or semi-circular cross-sectional contour, which are disposed at spaced intervals, therefore at 45 from each other, around the tube periphery.

Inthese two examples, the eight rectilinear splines or grooves of crescent-shaped cross-sectional contour have a cross-sectional passage area permitting the flow of a cooling fluid output adequate'for accompanying an oxygen output of the order of 5 Nm lmn in the central tube under an upstream pressure of about 10 bars psi).

However, in the second example with a cooling fluid consisting of a mixture of water and domestic fuel oil, the total cross-sectional passage area of the splines or grooves 14 (and therefore the radius of each spline or groove) is greater than that of the first example, wherein the cooling fluid only consists of domestic fueloil.

In all cases, before converting the metal to be refined a suitable scavenging gas is blown through the circuit consisting of said splines or grooves 14 and also through the central tube 10 in order to protect the tip of these splines and also of the central tube against any clogging by a foreign substance from within the converter, however without allowing cooling liquid to flow into the converter in the horizontal inoperative posi' tion.

Then, when the metal to be refined is present in the bottom ofthe converter, there is effected a switching which consists in substituting pure oxygen for the scavenging gas in the central tube 10, and fuel-oil or a water and fuel-oil mixture for the scavenging gas in the circuit comprising the splines 14. Then the converter is raised to its vertical position for performing the blowing process.

At the end of the conversion process the reverse operation is performed, i.e., after having inclined or dumped the converter, on the one hand scavenging gas is substituted for the oxygen in the central tube and on the other hand scavenging gas is substituted for the fuel-oil or water and fuel-oil mixture in the splines.

By adhering to this procedure any risk of pouring fuel-oil or water into the empty converter, just before charging the same with molten metal to be refined, which would cause strong projections, is safely eliminated.

Of course, this invention should not be construed as being limited by the specific embodiments described and illustrated herein, and by the details thereof given by way of example, since many modifications and variations may be made thereto without departing from the basic principles of the invention as set forth in the appended claims.

.We claim:

1. A tuyere and means for cooling the same in a converter, said tuyere comprising:

an inner tube providing an axial circuit means for the passage therethrough of an oxidizing gas;

an outer tube concentrically positioned around said inner tube; and

a plurality of point protrusions extending from one of said tubes into contact with the other of said tubes, said point protrusions providing means for centrally spacing said outer tube about said inner tube and forming an annular space therebetween, said annular space providing a peripheral circuit means for injecting a cooling agent into said converter peripherally of said oxidizing gas in a liquid state up to the top of said tuyere.

2. A device as claimed in claim 1, wherein said point protrusions are located at different heights along said tuyere.

3. A device as claimed in claim 1, wherein said point protrusions extend outwardly from the outer surface of said inner tube.

4. A device 'as claimed in claim 1, wherein said point protrusions extend inwardly from the inner surface of said outer tube. 

1. A tuyere and means for cooling the same in a converter, said tuyere comprising: an inner tube providing an axial circuit means for the passage therethrough of an oxidizing gas; an outer tube concentrically positioned around said inner tube; and a plurality of point protrusions extending from one of said tubes into contact with the other of said tubes, said point protrusions providing means for centrally spacing said outer tube about said inner tube and forming an annular space therebetween, said annular space providing a peripheral circuit means for injecting a cooling agent into said converter peripherally of said oxidizing gas in a liquid state up to the top of said tuyere.
 2. A device as claimed in claim 1, wherein said point protrusions are located at different heights along said tuyere.
 3. A device as claimed in claim 1, wherein said point protrusions extend outwardly from the outer surface of said inner tube.
 4. A device as claimed in claim 1, wherein said point protrusions extend inwardly from the inner surface of said outer tube. 